Instead of just scrolling through a touchscreen, talking or pushing buttons, users can manipulate the face of the prototype to interact with the display in more ways.

Exhibited at the ongoing ACM CHI Conference on Human Factors in Computing Systems in Toronto, the prototype is being billed as a way to overcome the small form factor and input limitations on standard smartwatches, unlocking their powerful computer potential.

Users can twist, pan in two dimensions, tilt or click the prototype's face, as well as using the conventional scrolling or button functions.

Applications include moving and zooming around a map on the display without fingers obscuring the view, clicking the face to snap a photo or twisting the face to adjust the volume on a music player app.

A demo on YouTube also shows how the prototype can be used to play the first-person shooter "Doom," with panning, twisting and clicking motions serving as controls.

Users also don't have to lift their fingers from the device to re-target an object or menu item.

"Since our fingers are large, and people want smartwatches to be small, we have to go beyond traditional input techniques," Gierad Laput, a PhD student at Carnegie Mellon's Human-Computer Interaction Institute, wrote in an email.

"Digitizing watchface mechanical movements offers expressive interaction capabilities without occluding the screen. It is a simple yet clever idea, and it is easy to implement."

The approach is cheap and potentially compact, the researchers including Chris Harrison, assistant professor of human-computer interaction, wrote in a related paper.

Further development of the watch could add functions such as 3D pan, yaw, pitch and roll, enhancing the input options.

The researchers are interested in commercializing the technology but have no concrete plans yet, Laput said.

With Samsung, Sony and other major manufacturers turning out wrist computers, the smartwatch industry was worth about $700 million in 2013 and is expected to reach $2.5 billion this year, according to Zurich-based research firm Smartwatch Group.